In an automatic painting system the pieces to be painted are transported by a belt conveyor while they are exposed to the paint spray.
Inevitably the residual paint gathers on the conveyor and, if it were not removed therefrom, it would soil the resting surface of the pieces being painted subsequently.
First attempts to clean the belt of the conveyor were by means of doctors or scrapers, that were pushed against the surface to be cleaned.
These have achieved a certain efficacy only with the belts constituted by a set of steel belts placed side by side, but were inadequate in the case of a continuous belt made of synthetic material.
Yet, the belt or multiple-wire conveyors have a further inconvenience, because they allow the paint to infiltrate between the belts or between the wires thus causing the lower panel surface to be soiled and the paint to be wasted.
To avoid this problem, conveyors with protective covers made of a paper sheet or with single disposable sheets of paper have been used.
In this case the danger of soiling the workpiece supporting surfaces was avoided, but the considerable use of paper and the difficulties with its disposal made such solution disadvantageous.